Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
  • H10K85/30—Coordination compounds
  • H10K85/341—Transition metal complexes, e.g. Ru(II)polypyridine complexes
  • H10K85/342—Transition metal complexes, e.g. Ru(II)polypyridine complexes comprising iridium
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K50/00—Organic light-emitting devices
  • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
  • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
  • H10K50/125—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers specially adapted for multicolour light emission, e.g. for emitting white light
  • H10K50/13—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers specially adapted for multicolour light emission, e.g. for emitting white light comprising stacked EL layers within one EL unit
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K50/00—Organic light-emitting devices
  • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
  • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
  • H10K50/125—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers specially adapted for multicolour light emission, e.g. for emitting white light
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K50/00—Organic light-emitting devices
  • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
  • H10K50/14—Carrier transporting layers
  • H10K50/16—Electron transporting layers

Definitions

• This disclosure relates in general to organic electronic devices and particularly to devices used for lighting.
• organic electronic devices such as organic light emitting diodes (“OLED”), that make up OLED displays or OLED lighting devices
• OLED organic light emitting diodes
• the organic active layer is sandwiched between two electrical contact layers.
• at least one of the electrical contact layers is light- transmitting, and the organic active layer emits light through the light- transmitting electrical contact layer upon application of a voltage across the electrical contact layers.
• organic electroluminescent compounds As the active component in light-emitting diodes. Simple organic molecules, conjugated polymers, and organometallic complexes have been used. Devices frequently include one or more charge transport layers, which are positioned between a photoactive (e.g., light-emitting) layer and an electrical contact layer. A device can contain two or more contact layers. A hole transport layer can be positioned between the photoactive layer and the hole-injecting contact layer. The hole-injecting contact layer may also be called the anode. An electron transport layer can be positioned between the photoactive layer and the electron-injecting contact layer. The electron-injecting contact layer may also be called the cathode. Charge transport materials can also be used as hosts in combination with the photoactive materials.
• an organic electronic device comprising in order: an anode, a hole transport layer, an emissive layer, an electron transport layer, and a cathode, wherein the emissive layer comprises at least one first electroluminescent material and the electron transport layer consists essentially of one or more electroluminescent materials which are different from the first electroluminescent material, and wherein the device has white light emission.
• one or more of the electroluminescent materials is an iridium complex having organic ligands.
• FIG. 1 includes an illustration of one example of a prior art organic electronic device.
• FIG. 2 includes another illustration of a prior art organic electronic device where three emitters are mixed in one layer.
• FIG. 3 includes another illustration of a prior art organic electronic device where three emitters are distributed in three separate layers.
• FIG. 4 includes another illustration of a prior art organic electronic device where three emitters are distributed in two separate layers.
• FIG. 5 includes an illustration of an organic electronic device according to one embodiment of the present invention.
• blue is intended to mean radiation that has an emission maximum at a wavelength in a range of approximately 380-495 nm.
• charge transport when referring to a layer, material, member, or structure is intended to mean such layer, material, member, or structure facilitates migration of such charge through the thickness of such layer, material, member, or structure with relative efficiency and small loss of charge.
• Hole transport materials facilitate positive charge migration; electron transport materials facilitate negative charge migration.
• CRT refers to the color rendering index devised by the
• CIE International Commission on Illumination
• dopant is intended to mean a material, within a layer including a host material, that changes the electronic characteristic(s) or the targeted wavelength(s) of radiation emission, reception, or filtering of the layer compared to the electronic characteristic(s) or the wavelength(s) of radiation emission, reception, or filtering of the layer in the absence of such material.
• a dopant of a given color refers to a dopant which emits light of that color.
• electroactive material refers to a material that emits light in response to the passage of an electric current or to a strong electric field.
• emissive refers to a layer which is light-emitting.
• green is intended to mean radiation that has an emission maximum at a wavelength in a range of approximately 495-570 nm.
• hole injection when referring to a layer, material, member, or structure, is intended to mean such layer, material, member, or structure facilitates injection and migration of positive charges through the thickness of such layer, material, member, or structure with relative efficiency and small loss of charge.
• host material is intended to mean a material, usually in the form of a layer, to which a dopant may or may not be added.
• the host material may or may not have electronic characteristic(s) or the ability to emit, receive, or filter radiation. When a dopant is present in a host material, the host material does not significantly change the emission wavelength of the dopant material.
• range is intended to mean radiation that has an emission maximum at a wavelength in a range of approximately 590-620 nm.
• photoluminescence quantum yield is intended to mean the ratio of photons absorbed to photons emitted through luminescence.
• red is intended to mean radiation that has an emission maximum at a wavelength in a range of approximately 620-780 nm.
• small molecule when referring to a compound, is intended to mean a compound which does not have repeating monomeric units. In one embodiment, a small molecule has a molecular weight no greater than approximately 2000 g/mol.
• substrate is intended to mean a base material that can be either rigid or flexible and may be include one or more layers of one or more materials, which can include, but are not limited to, glass, polymer, metal or ceramic materials or combinations thereof.
• the substrate may or may not include electronic components, circuits, or conductive members.
• white light refers to the effect of combining the visible colors of light in suitable proportions so that the light appears white or colorless to the human eye. Since the impression of white is obtained by three summations of light intensity across the visible spectrum, the number of combinations of light wavelengths that produce the sensation of white is practically infinite. The impression of white light can also be created by mixing appropriate intensities of the primary colors of light, red, green and blue (RGB), a process called additive mixing, as seen in many display technologies.
• RGB red, green and blue
• yellow is intended to mean radiation that has an emission maximum at a wavelength in a range of approximately 570-590 nm.
• the device (1 ) consists of an anode (100), a hole injection layer (200), a hole transport layer (300), a light emitting layer (400), an electron transport layer (500), an electron injection layer (600), and a cathode (700).
• a support, not shown can be present adjacent either the anode or the cathode.
• the light emitting layer there are two emitters, such as blue and yellow, such that the combined emission results in a white color.
• three or four emitters are used. In the discussion which follows, three emitters will be used for illustrative purposes. However, more than three could be used.
• FIG. 2 a prior art device (2) is shown in which three emitters, having red, green and blue emission, are present in a single emissive layer (layer 401 ).
• layer 401 a single emissive layer
• the fabrication process is cheaper.
• This single emissive layer approach therefore has the drawback of reduced device performance.
• FIG. 3 a prior art device is shown in which there is a separate layer for each emitter, layers 402, 403, and 404. With three separate emitting layers, each color can be individually optimized with its own host to achieve maximal efficiency. However, the fabrication process is more complicated with three separate layers.
• a compromise may be made by using two emitting layers, in which one of the layers having green and red emitters and the other layer having a blue emitter. This is shown in FIG. 4, where layer 405 has red and green emitters, and layer 406 has a blue emitter. It is much easier to find a common host for green and red emitters and maintain their efficiency, while the blue layer can be optimized separately.
• the fabrication process is easier for this architecture with dual emissive layers due to the elimination of one layer, but it still has one extra layer than the single emissive layer approach.
• FIG. 5 One embodiment of the present invention is shown in FIG. 5.
• the second emitter layer is eliminated and its function is combined with the electron transport layer (501 ).
• the electron transport layer consists only of one or more electroluminescent materials that are different from the first electroluminescent material, without the presence of a host.
• the devices disclosed in this invention have the same number of layers as the single emissive layer devices (FIG. 2), but the architecture allows the separate optimization of blue efficiency to achieve maximal device performance.
• the first electroluminescent material has blue emission color
• the electron transport layer consists essentially of an electroluminescent material having yellow emission color.
• the first electroluminescent material has blue-green emission color
• the electron transport layer consists essentially of an electroluminescent material having orange-red to red emission color.
• the first electroluminescent material has blue emission color
• the electron transport layer consists essentially of an electroluminescent material having orange-red emission color.
• the emissive layer comprises at least one electroluminescent ("EL") material.
• EL electroluminescent
• Any EL material can be used in the devices, including, but not limited to, small molecule organic fluorescent compounds, luminescent metal complexes, conjugated polymers, and mixtures thereof.
• fluorescent compounds include, but are not limited to, chrysenes, pyrenes, perylenes, rubrenes, coumarins, anthracenes, thiadiazoles, derivatives thereof, arylamino derivatives thereof, and mixtures thereof.
• metal complexes include, but are not limited to, metal chelated oxinoid compounds, such as tris(8-hydroxyquinolato)aluminum (Alq3); cyclometalated iridium and platinum electroluminescent
• conjugated polymers include, but are not limited to poly(phenylenevinylenes), polyfluorenes, poly(spirobifluorenes), polythiophenes, poly(p-phenylenes), copolymers thereof, and mixtures thereof.
• red to orange light-emitting materials include, but are not limited to, complexes of Ir having phenylquinoline or
• Red light-emitting materials have been disclosed in, for example, US patent 6,875,524, and published US application 2005-0158577.
• green to blue-green light-emitting materials include, but are not limited to, complexes of Ir having phenylpyridine ligands, bis(diarylamino)anthracenes, and polyphenylenevinylene polymers.
• Green light-emitting materials have been disclosed in, for example, published PCT application WO 2007/021 1 17.
• blue light-emitting materials include, but are not limited to, complexes of Ir having phenylpyridine or phenylimidazole ligands, diarylanthracenes, diaminochrysenes, diaminopyrenes, and polyfluorene polymers. Blue light-emitting materials have been disclosed in, for example, US patent 6,875,524, and published US applications 2007- 0292713 and 2007-0063638.
• yellow light-emitting materials include, but are not limited to, complexes of Ir having phenylquinoline or phenylisoquinoline ligands, periflanthenes, fluoranthenes, and perylenes. Yellow light- emitting materials have been disclosed in, for example, US patent
• the electroluminescent material is an organometallic complex.
• the organometallic complex is cyclometallated.
• cyclometallated it is meant that the complex contains at least one ligand which bonds to the metal in at least two points, forming at least one 5- or 6-membered ring with at least one carbon-metal bond.
• the light-emitting material is a cyclometalated complex of iridium or platinum.
• Such materials have been disclosed in, for example, U.S. Patent 6,670,645 and Published PCT Applications WO 03/063555, WO 2004/016710, and WO 03/040257.
• the organometallic complex is electrically neutral and is a tris-cyclometallated complex of iridium having the formula lrl_3 or a bis-cyclometallated complex of iridium having the formula lrl_ 2 Y.
• L is a monoanionic bidentate cyclometalating ligand coordinated through a carbon atom and a nitrogen atom.
• L is an aryl N-heterocycle, where the aryl is phenyl or napthyl, and the N-heterocycle is pyridine, quinoline, isoquinoline, diazine, pyrrole, pyrazole or imidazole.
• Y is a monoanionic bidentate ligand.
• L is a phenylpyridine, a phenylquinoline, or a phenylisoquinoline.
• Y is a ⁇ - dienolate, a diketimine, a picolinate, or an N-alkoxypyrazole.
• the ligands may be unsubstituted or substituted with F, D, alkyl, perfluororalkyl, alkoxyl, alkylamino, arylamino, CN, silyl, fluoroalkoxyl or aryl groups.
• organometallic iridium complexes having red to red-orange emission are bis or tris complexes of ligands
• N-coordinating ring is quinoline or isoquinoline and the C-coordinating ring is phenyl.
• the N-coordinating ring is pyridine and the C-coordinating ring is a diazine.
• the emitted color can be tuned by the selection and combination of electron-donating and electron-withdrawing substituents. In addition, the color is tuned by the choice of third ligand in the bis-cyclometallated complexes. Shifting the color to shorter
• wavelengths is accomplished by (a) selecting one or more electron- donating substituents for the N-coordinating ring; and/or (b) selecting one or more electron-withdrawing substituents for C-coordinating ring; and/or (c) selecting a bis-cyclometallated complex with a third ligand which is a picolinate or an hydroxyethylpyrazole. Conversely, shifting the color to longer wavelengths is accomplished by (a) selecting one or more electron- withdrawing substituents for the N-coordinating ring; and/or (b) selecting one or more electron-donating substituents for C-coordinating ring; and/or (c) selecting a bis-cyclometallated complex with a third ligand which is an beta-diketonate.
• electron-donating substituents include, but are not limited to, alkyl, alkoxy silyl, and dialkylamino.
• electron-withdrawing substituents include, but are not limited to, F, CN, fluoroalkyl, and fluoroalkoxy.
• organometallic iridium complexes having red to red- orange emission color include, but are not limited to compounds R1 through R1 1 below.
• organometallic iridium complexes having yellow emission are bis or tris complexes of ligands coordinated through nitrogen in one ring (N-coordinating ring) and carbon in a second ring (C- coordinating ring).
• N-coordinating ring is quinoline or isoquinoline and the C-coordinating ring is phenyl.
• the N-coordinating ring is pyridine and the C-coordinating ring is phenyl or a diazine. The emitted color can be tuned as discussed above.
• organometallic iridium complexes having yellow emission color include, but are not limited to compounds Y1 through Y1 1 below.
• organometallic iridium complexes having blue to blue-green emission are bis or tris complexes of ligands coordinated through nitrogen in one ring (N-coordinating ring) and carbon in a second ring (C-coordinating ring).
• N-coordinating ring is pyridine and the C-coordinating ring is phenyl, pyridine, pyrimidine, or a diazine.
• the N- coordinating ring is a diazine and the C-coordinating ring is phenyl.
• the ligand having both N- and C-coordinating rings is a 7,8-benzoquinoline or a 1 ,7-phenanthroline. The emitted color can be tuned as discussed above.
• organometallic iridium complexes having blue to blue- green emission color include, but are not limited to compounds B1 through B1 1 below.
• the emissive layer further comprises a host material to improve processing and/or electronic properties.
• host materials include, but are not limited to, carbazoles, indolocarbazoles, chrysenes, phenanthrenes, triphenylenes, phenanthrolines, triazines, naphthalenes, anthracenes, quinolines, isoquinolines, quinoxalines, phenylpyridines, benzodifurans, metal quinolinate complexes, deuterated analogs thereof, and combinations thereof.
• the emissive layer further comprises a third EL material.
• the emissive layer consists essentially of a host and a blue to blue-green dopant, which is a cyclometallated complex of iridium.
• the host is selected from the group consisting of indolocarbazoles, triazines, chrysenes, deuterated analogs thereof, and combinations thereof.
• the emissive layer consists essentially of a host and a blue to blue-green dopant which is selected from a
• the host is selected from arylanthracene derivatives.
• the total amount of EL dopant in the emissive layer is 1 -30% by weight, based on the total weight of the layer; in some embodiments, 5-20% by weight.
• the electron transport layer consists essentially of one or more electroluminescent materials which are different from the first EL material in the emissive layer.
• the electron transport layer consists essentially of an iridium complex having organic ligands.
• the photoluminescent quantum yield is the photoluminescent quantum yield
• the PLQY can be measured using equipment designed to determine the value of thin films such as an integrating sphere. However, frequently the PLQY is more conveniently measured in solution.
• the solution PLQY can be determined using a luminance spectrophotometer. In some embodiments, the PLQY is determined for a solution of the iridium complex in an organic solvent. In some embodiments, this solution PLQY is greater than 20%; in some embodiments, greater than 50%; in some embodiments, greater than 70%.
• the electron transport layer consists essentially of an iridium complex having yellow emission. In some embodiments, the electron transport layer consists essentially of an iridium complex having orange-red to red emission.
• the other layers in the device can be made of any materials that are known to be useful in such layers.
• a substrate may be present adjacent the anode or the cathode.
• the substrate is adjacent the anode.
• the substrate is a base material that can be either rigid or flexible.
• the substrate may include one or more layers of one or more materials, which can include, but are not limited to, glass, polymer, metal or ceramic materials or combinations thereof.
• the substrate may or may not include electronic components, circuits, or conductive members.
• the anode is an electrode that is particularly efficient for injecting positive charge carriers. It can be made of, for example materials containing a metal, mixed metal, alloy, metal oxide or mixed-metal oxide, or it can be a conducting polymer, and mixtures thereof. Suitable metals include the Group 1 1 metals, the metals in Groups 4, 5, and 6, and the Group 8 10 transition metals. If the anode is to be light-transmitting, mixed-metal oxides of Groups 12, 13 and 14 metals are generally used. Examples of suitable materials include, but are not limited to, indium-tin- oxide ("ITO").
• ITO indium-tin- oxide
• the anode comprises a fluorinated acid polymer and conductive nanoparticles. Such materials have been described in, for example, US Patent 7,749,407.
• the hole injection layer comprises hole injection material.
• hole injection material is electrically conductive or semiconductive material.
• the hole injection material can be a polymeric material, such as polyaniline (PANI) or polyethylenedioxythiophene (PEDOT), which are often doped with protonic acids.
• the protonic acids can be, for example, poly(styrenesulfonic acid), poly(2-acrylamido-2-methyl-1 -propanesulfonic acid), and the like.
• the hole injection material can comprise charge transfer compounds, and the like, such as copper phthalocyanine and the tetrathiafulvalene-tetracyanoquinodimethane system (TTF-TCNQ).
• TTF-TCNQ tetrathiafulvalene-tetracyanoquinodimethane system
• the hole injection layer is made from a dispersion of a conducting polymer and a colloid-forming polymeric acid. Such materials have been described in, for example, U.S. patent 7,250,461 , published U.S. patent applications 2004-0102577, 2004-0127637, and 2005
• the hole injection layer comprises a fluorinated acid polymer and conductive nanoparticles.
• a fluorinated acid polymer and conductive nanoparticles.
• hole transport materials for the hole transport layer have been summarized for example, in Kirk-Othmer Encyclopedia of Chemical Technology, Fourth Edition, Vol. 18, p. 837-860, 1996, by Y. Wang. Both hole transporting molecules and polymers can be used.
• hole transporting molecules are: N,N'-diphenyl-N,N'-bis(3- methylphenyl)-[1 ,1 '-biphenyl]-4,4'-diamine (TPD), 1 ,1 -bis[(di-4-tolylamino) phenyljcyclohexane (TAPC), N,N'-bis(4-methylphenyl)-N,N'-bis(4- ethylphenyl)-[1 ,1 '-(3,3'-dimethyl)biphenyl]-4,4'-diamine (ETPD), tetrakis-(3- methylphenyl)-N,N,N',N'-2,5-phenylenediamine (PDA), a-phenyl-4- ⁇ , ⁇ - diphenylaminostyrene (TPS), p-(diethylamino)benzaldehyde
• hole transporting polymers are polyvinylcarbazole, (phenylmethyl)- polysilane, and polyaniline. It is also possible to obtain hole transporting polymers by doping hole transporting molecules such as those mentioned above into polymers such as polystyrene and polycarbonate.
• triarylamine polymers are used, especially triarylamine-fluorene copolymers.
• the polymers and copolymers are examples of the polymers and copolymers.
• the hole transport layer further comprises a p-dopant.
• the hole transport layer is doped with a p-dopant.
• p-dopants include, but are not limited to, tetrafluorotetracyanoquinodimethane (F4-TCNQ) and perylene- 3,4,9,10-tetracarboxylic-3,4,9,10-dianhydride (PTCDA).
• the photoactive layer 400 can be a light-emitting layer that is activated by an applied voltage (such as in a light-emitting diode or light-emitting electrochemical cell), a layer of material that responds to radiant energy and generates a signal with or without an applied bias voltage (such as in a photodetector).
• the electroactive layer comprises an organic
• the electron injection layer can comprise a material selected from the group consisting of Li-containing organometallic compounds, LiF, Li 2 0, Cs-containing organometallic compounds, CsF, Cs 2 0, and Cs 2 C0 3 .
• the material deposited for the electron injection layer reacts with the underlying electron transport layer and/or the cathode and does not remain as a measurable layer.
• the cathode is an electrode that is particularly efficient for injecting electrons or negative charge carriers.
• the cathode can be any metal or nonmetal having a lower work function than the anode.
• Materials for the cathode can be selected from alkali metals of Group 1 (e.g., Li, Cs), the Group 2 (alkaline earth) metals, the Group 12 metals, including the rare earth elements and lanthanides, and the actinides. Materials such as aluminum, indium, calcium, barium, samarium and magnesium, as well as combinations, can be used.
• each of the component layers is preferably determined by balancing the positive and negative charges in the emitter layer to provide a device with high electroluminescence efficiency. It is understood that each functional layer can be made up of more than one layer.
• the device consists essentially of, in order, an anode, a hole injection layer, a hole transport layer, an emissive layer, an electron transport layer, an electron injection layer, and a cathode, where the emissive layer and the electron transport layer are as described above.
• the different layers have the following range of thicknesses: anode, 500-5000 A, in one embodiment 1000-2000 A; hole injection layer, 50-3000 A, in one embodiment 200-1 000 A; hole transport layer, 50-2000 A, in one embodiment 200-1000 A; emissive layer, 10-2000 A, in one embodiment 100-1000 A; electron transport layer, 100-2000 A, in one embodiment 200-1500 A; electron injection layer, 1 -25 A, in one embodiment 5-15 A; cathode, 200-10000 A, in one embodiment 300-5000 A.
• the desired ratio of layer thicknesses will depend on the exact nature of the materials used.
• the electron transport layer is formed by vapor deposition.
• the other device layers can be formed by any deposition technique, or combinations of techniques, including vapor deposition, liquid deposition, and thermal transfer. Conventional vapor deposition techniques can be used, as discussed above.
• the organic layers can be applied from solutions or dispersions in suitable solvents, using conventional coating or printing techniques, including but not limited to spin-coating, dip-coating, roll-to-roll techniques, ink-jet printing, continuous nozzle printing, screen- printing, gravure printing and the like.
• a suitable solvent for a particular compound or related class of compounds can be readily determined by one skilled in the art.
• non-aqueous solvents can be relatively polar, such as Ci to C 2 o alcohols, ethers, and acid esters, or can be relatively non-polar such as Ci to C-
• suitable liquids for use in making the liquid composition either as a solution or dispersion as described herein, comprising the new
• chlorinated hydrocarbons such as methylene chloride, chloroform, chlorobenzene
• aromatic hydrocarbons such as methylene chloride, chloroform, chlorobenzene
• hydrocarbons such as substituted and non-substituted toluenes and xylenes
• polar solvents such as tetrahydrofuran (THP), N-methyl pyrrolidone) esters (such as ethylacetate) alcohols (isopropanol), keytones (cyclopentatone) and mixtures thereof.
• Suitable solvents for electroluminescent materials have been described in, for example, published PCT application WO 2007/145979.
• the device is fabricated by liquid deposition of the hole injection layer, the hole transport layer and the emissive layer, and by vapor deposition of the electron transport layer, an electron injection layer and the cathode.
• the efficiency of devices made with the new compositions described herein can be further improved by optimizing the other layers in the device.
• more efficient cathodes such as Ca, Ba or LiF can be used.
• Shaped substrates and novel hole transport materials that result in a reduction in operating voltage or increase quantum efficiency are also applicable.
• HIJ-1 is a hole injection material and is made from an aqueous dispersion of an electrically conductive polymer and a polymeric fluorinated sulfonic acid. Such materials have been described in, for example, published U.S. patent applications US 2004/0102577, US
• NPB is ⁇ , ⁇ '-Bis- (1 -naphthalenyl)-N,N'-bis-phenyl-(1 ,1 '-biphenyl)-4,4'- diamine Blue 1 is shown below. Such materials have been described in, for example, published US patent application US 2010-0187983.
• the dopantY1 1 is prepared using procedures analogous to those shown in, for example, US patent 6,670,645 and published US patent application 2010-0148663.
• ETM-1 is tetrakis(8-hydroxyquinolinato)zirconium, known as "ZrQ”.
• Example A the electron transport layer was ETM-1 .
• Example 1 the electron transport layer was Y1 1 .
• the devices had the following device layers, in the order listed, where all percentages are by weight, based on the total weight of the layer.
• ITO indium tin oxide
• hole injection layer HIJ-1 (50 nm)
• cathode Al (100 nm)
• the devices were prepared by depositing the layers on the glass substrate.
• the hole injection layer was deposited by spin coating from an aqueous dispersion. All other layers were applied by evaporative deposition.
• the devices were characterized by measuring their (1 ) current- voltage (l-V) curves, (2) electroluminescence radiance versus voltage, and (3) electroluminescence spectra versus voltage. All three measurements were performed at the same time and controlled by a computer.
• the current efficiency (cd/A) of the device at a certain voltage is determined by dividing the electroluminescence radiance of the LED by the current density needed to run the device.
• the power efficacy (Lm/W) is the current efficiency divided by the operating voltage.
• the correlated color temperature (“CCT”) was calculated from the electroluminance spectra. The results are given in Table 1 .
• EQE external quantum efficiency
• CIEx.y x and y color coordinates according to the CLE. chromaticity scale (Commission Internationale de L'Eclairage, 1931 )
• Example 1 shows that the Ir complex can be used as an electron transport layer in a fluorescent blue device.
• the devices give comparable efficiency and blue color.
• the device of Example 1 has a 1 V lower operating voltage.
• This example illustrates the performance of a white light device having an iridium complex as the electron transport layer.
• Example 2 had the following device layers, in the order listed, where all percentages are by weight based on the total weight of the layer.
• substrate glass
• ITO indium tin oxide
• hole injection layer HIJ-1 (50 nm)
• cathode Al (1 00 nm)
• the device was prepared by depositing the layers on the glass substrate, as in Example 1 .
• Example 2 The device was characterized as described above for Example 1 . The results are given in Table 2. Table 2. Device Results @1000 nits °K @2000 nits
• EQE external quantum efficiency
• CIEx.y x and y color coordinates according to the CLE. chromaticity scale (Commission Internationale de L'Eclairage, 1931 )
• T50 is the time in hours for the luminance to reach 50% of its initial value.

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